1. Field of the Invention
This invention relates generally to four stroke internal combustion engines and particularly to a means for varying the volume of a combustion chamber in combination with a spring loaded intake valve in a fuel injected internal combustion engine.
2. Prior Art
One of the main objectives toward operating an optimally functioning internal combustion engine is to maintain a constant combustion chamber pressure throughout all operating ranges. This result is typically achieved by varying the volume of the combustion chamber during the operating cycle of the engine. When the engine is running in the lower RPM range, it is desirable to utilize higher compression ratios in order to obtain more power to overcome the static friction forces of the engine. At higher RPM, the compression ratio may be reduced by increasing the volume of the combustion chamber at such a rate as to keep the combustion chamber pressure constant or near constant. That is, as the speed of the engine is increased, a larger quantity of fuel and air is introduced into the combustion chamber. This increased volume of intake charge gives rise to an increased pressure in the combustion chamber. Increasing the volume of the combustion chamber in like proportion allows the pressure therein to remain relatively constant.
However, when the volume of the combustion chamber is made too small (i.e. at low engine speed), the retarding forces acting on the downwardly traveling piston on the power stroke results in a substantial power loss as the piston approaches bottom dead center (BDC).
Of the prior art devices which disclose varying the combustion chamber volume for the purpose of increasing the operating efficiency thereof, none provide a means for decreasing the retarding (vacuum) forces acting on the downwardly traveling piston on the power stroke. Representative efforts at providing variable volume combustion chambers are disclosed in the following U.S. Pat. Nos.:
______________________________________ 4,625,684 4,539,946 4,516,537 4,449,489 4,313,403 4,286,552 4,187,808 3,970,056 ______________________________________
It is a primary object of the instant invention to provide an internal combustion engine wherein the compression ratio is varied by means of a reciprocally moving piston used in conjunction with a spring loaded intake have instead of the ordinary poppet valve.
Another object of the present invention is to provide a combustion chamber in an internal combustion engine capable of maintaining a relatively constant combustion chamber pressure throughout all operating RPM ranges.
It is a still further object of the present invention to provide a combustion chamber for an internal combustion engine capable of operating, while at idle, at an unusually high compression ratio, while at the same time providing for the reduction of substantially all of the retarding forces caused by negative pressure on the downwardly traveling piston during the intake and power strokes.
These and other objects will be apparent hereinafter.